+12v feed powers on unlock / powers off on lock ?

[archersam]

I had thought I had the solution until I tested it today so wondering if any bright spark has a solution (did search however didn't find the answer)

I was going to use the footwell LED power to light my knight rider bonnet light as having observed the LED light it looked ideal:
- would come on when unlocked
- would go off when ignition turned on
- would come on when ignition turned off
- would go off when locked

This was going to be one of two supplies using diodes the other being when ignition is live.

So I thought I would mock it up and found that it behaves like this:
- unlock the car and footwell light comes on as well as knight rider light - PERFECT.
- turn on the ignition and footwell light goes out as expected BUT knight rider light stays illuminated and then after 20 or 30 seconds, goes off, comes back on again and then is only partly lit.
- lock the car and footwell light goes out as as does knight rider light - PERFECT.

I am guessing there is still some voltage to the lamp when it is "off" which is impacting the knight rider and I guess the BCM is keeping it in standby mode or something?

So after all that does anyone know of a live feed that will come on when unlocking and go off with locking (either immediately or timed)

 

[paddy26]

Could the coming/leaving home function be used?

 

[Deaky]

Use an optocoupler relay to switch it triggered by the courtesy circuit

 

[archersam]

Use an optocoupler relay to switch it triggered by the courtesy circuit

Ok I’ve seen them but I understood that was for having alternative power sources for feeding one supply - which I can do with diodes as know how they all work.

I’m not sure the optocoupler will fix the issue I am experiencing : which is that the power to the footwell led does not go off when ignition is switched on as I had expected……

OR are you saying that by using an opto relay then it will switch off to zero Volts when interior light goes off?

 

[Deaky]

The courtesy circuit is switched using PWM on the -ve side. +12v stays on.

 

[archersam]

The courtesy circuit is switched using PWM on the -ve side. +12v stays on.

ah ok that makes sense as of course I didn’t test the footwell live during engine running as wrongly assumed it would be off ¯\_(ツ)_/¯

 

[archersam]

The courtesy circuit is switched using PWM on the -ve side. +12v stays on.

Mmm thinking outside of the box. If i used both the earth and power for the footwell led in the circuit for the knight rider then that might give me what I want. Shame it’s now dark ha ha

 

[Howzat]

Have you seen the main thread for this type of light?

Apparently there's an anomaly with these lights not working with the ignition on when wired to the welcome lights due to voltage drop.
Might be exactly what you're looking for though.

 

[archersam]

Have you seen the main thread for this type of light?

Apparently there's an anomaly with these lights not working with the ignition on when wired to the welcome lights due to voltage drop.
Might be exactly what you're looking for though.

Thanks for that, yes I’d seen the thread as was on it myself. Honestly I didn’t fully understand the last big text about interior light voltage HOWEVER the comment from @Deaky relating to it switching off on the negative gave me an idea so I’ve been up early and:

I wired it as follows:
- neg knight rider to neg interior footwell
- positive knight rider to positive interior footwell

Now it WORKS as i want

- unlock turns on
- ignition on turns off
- ignition off turns on
- lock turns off

Many thanks for the inputs really appreciated it as I knew the subject had come up a few times just I had a slightly different requirement.

I already had installed a pair of spare cables from footwell to the engine bay so now need to find the time to wire it all up as I want

 

[archersam]

Minor update. Didn’t think about fact that whilst the footwell earth would disconnect the other earth for the ignition live wouldn’t and so it continues to complete a circuit.

Now I’m guessing optocoupler might fix that snd some have arrived however don’t really have time before a euro trip.

So now it currently works with no earth connected in the footwell area however still comes on with lock and goes off with unlock. Stays on with ignition on.

The only weird thing it does is it stay on permanently when ignition is off, doors are closed and the footwell lights have gone to sleep and gone off. It only turns off when locked.

Will get me into better habits of locking it at home during the day rather than just at night (secure gates with my office looking directly out onto them)

 

[Deaky]

I don’t get why you need to connect it to the ign circuit. Can’t you just connect it to the courtesy circuit?

unlock van, courtesy lights come on
start engine, courtesy lights go off
stop engine and remove key, courtesy lights come on
lock the door, courtesy lights go off

 

[archersam]

I don’t get why you need to connect it to the ign circuit. Can’t you just connect it to the courtesy circuit?

unlock van, courtesy lights come on
start engine, courtesy lights go off
stop engine and remove key, courtesy lights come on
lock the door, courtesy lights go off

I ALSO want it to be on when the van is running/being driven and as you know the courtesy lights go off when ignition goes on and that means the bonnet light also goes off. I want it do BOTH things .

 

[Deaky]

Now it WORKS as i want

- unlock turns on
- ignition on turns off
- ignition off turns on
- lock turns off

Many thanks for the inputs really appreciated it as I knew the subject had come up a few times just I had a slightly different requirement.

I already had installed a pair of spare cables from footwell to the engine bay so now need to find the time to wire it all up as I want

Ahh ok.

unlock, comes on
ign on, stays on
key out, stays on
doors locked turns off

 

[Deaky]

So you could try this method using a changeover relay

Night rider +ve to permanent +12v (you could use the courtesy red/black but this will time out eventually if the doors aren’t locked)
Night rider -ve to the common pin on the relay
Courtesy switched -ve (brown/red) to the NC pin on the relay
Courtesy permanent -ve (brown) to the NO pin on the relay
Relay coil to ign live and ground

so when the ignition is off the night rider will turn on and off with the courtesy lights. When the ignition is on the relay will flip and give the night rider permanent -ve until the ignition is switched off

The only issue I can see is the night rider may reboot as the relay flips over

 

[archersam]

So you could try this method using a changeover relay

Night rider +ve to permanent +12v (you could use the courtesy red/black but this will time out eventually if the doors aren’t locked)
Night rider -ve to the common pin on the relay
Courtesy switched -ve (brown/red) to the NC pin on the relay
Courtesy permanent -ve (brown) to the NO pin on the relay
Relay coil to ign live and ground

so when the ignition is off the night rider will turn on and off with the courtesy lights. When the ignition is on the relay will flip and give the night rider permanent -ve until the ignition is switched off

The only issue I can see is the night rider may reboot as the relay flips over

Thanks @Deaky Sounds good, I am going away so will look into it when I get back. Other than it not going off if left unlocked it is almost doing what I want however its always good to get it perfect

Something like this I assume:

https://www.amazon.co.uk/Ehdis-Truck-Normally-Socket-Waterproof/dp/B01KFKDZ60/ref=sr_1_1_sspa?keywords=changeover+relay+12v&qid=1692084866&s=automotive&sprefix=changeover+rela%2Cautomotive%2C106&sr=1-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1